﻿<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8"/>
		<title>JS实现倒计时(时、分，秒) </title>
		<script language="javascript" type="text/javascript">
			function fnDateDiff(year, month, day, showDateDiff) {
				var now = new Date();
				var endDate = new Date(year, month - 1, day);
				var leftTime = endDate.getTime() - now.getTime();
				var leftsecond = parseInt(leftTime / 1000);
				var day1 = Math.floor(leftsecond / (60 * 60 * 24));
				var hour = Math.floor((leftsecond - day1 * 24 * 60 * 60) / 3600);
				var minute = Math.floor((leftsecond - day1 * 24 * 60 * 60 - hour * 3600) / 60);
				var second = Math.floor(leftsecond - day1 * 24 * 60 * 60 - hour * 3600 - minute * 60);
				var show = document.getElementById(showDateDiff);
				show.innerHTML = "距离" + year + "年" + month + "月" + day + "日还有：" + day1 + "天" + hour + "小时" + minute + "分" + second + "秒";
			}
			window.onload = function() {
				setInterval(function() {
					fnDateDiff(2020, 12, 31, 'showDateDiff');
				}, 1000);
			}
		</script>
	</head>

	<body>
		<div id="showDateDiff"></div>
	</body>

</html>